Jimwell spent 4/10 of $20 What fractional part of $20 was left. Write in decimal form

Jimwell spent 4/10 of $20, which is (4/10) * $20 = $<<4/10*20=8>>8.

The amount left is $20 - $8 = $<<20-8=12>>12.
The fractional part of $20 that was left is 12/20 = 0.6 in decimal form. Answer: \boxed{0.6}.